ceph/src/TODO

v0.17
- kclient: fix multiple mds mdsmap decoding
- kclient: fix mon subscription renewal
- crush: fix crush map creation with empty buckets (occurs on larger clusters)
- osdmap: fix encoding bug (crashes kclient); make kclient not crash
- msgr: simplified policy, failure model
- mon: less push, more pull
- mon: request routing
- mon cluster expansion
- osd: fix pg parsing, restarts on larger clusters

v0.18
- osd: basic ENOSPC handling
- big endian fixes (required protocol/disk format change)
- osd: improved object -> pg hash function; selectable
- crush: selectable hash function(s)
- mds restart bug fixes
- kclient: mds reconnect bug fixes
- fixed mds log trimming bug
- fixed mds cap vs snap deadlock
- filestore: faster flushing
- uclient,kclient: snapshot fixes
- mds: fix recursive accounting bug
- uclient: fixes for 32bit clients
- auth: 'none' security framework
- mon: "safely" bail on write errors (e.g. ENOSPC)
- mds: fix replay/reconnect race (caused (fast) client reconnect to fail)
- mds: misc journal replay, session fixes

v0.19
- ms_dispatch fairness
- kclient: bad fsid deadlock fix
- tids in fixed msg header (protocol change)
- feature bits during connection handshake
- remove erank from ceph_entity_addr
- disk format, compat/incompat bits
- journal format improvements
- kclient: cephx
- improved truncation
- cephx: lots of fixes
- mkcephfs: cephx support
- debian: packaging fixes

v0.20
- new filestore, journaling

- multiple mds fixes

- qa: snap test.  maybe walk through 2.6.* kernel trees?
- osd: rebuild pg log
- osd: handle storage errors
- rebuild mds hierarchy
- kclient: retry alloc on ENOMEM when reading from connection?

filestore
- throttling
- flush objects onto primary during recovery
- audit queue_transaction calls for dependencies
- convert apply_transaction calls in handle_map to queue?
  - need an osdmap cache layer?

bugs
- kclient: looping osd connection failures
[ 3974.417106] ceph: osd11 10.3.14.138:6800 connection failed
[ 3974.423295] ceph: osd11 10.3.14.138:6800 connection failed
[ 3974.429709] ceph: osd11 10.3.14.138:6800 connection failed
[ 3974.437863] ceph: osd11 10.3.14.138:6800 connection failed
[ 3974.451780] ceph: osd11 10.3.14.138:6800 connection failed
[ 3974.472879] ceph: osd11 10.3.14.138:6800 connection failed
[ 3974.479061] ceph: osd11 10.3.14.138:6800 connection failed
[ 3974.485138] ceph: osd11 10.3.14.138:6800 connection failed
[ 3974.491235] ceph: osd11 10.3.14.138:6800 connection failed
[ 3974.499103] ceph: osd11 10.3.14.138:6800 connection failed
[ 3974.508805] ceph: osd11 10.3.14.138:6800 connection failed
[ 3974.517429] ceph: osd11 10.3.14.138:6800 connection failed
[ 3974.585106] ceph: osd11 10.3.14.138:6800 connection failed
  ... crash some osds, then restart them ...?

- kclient: mds reconnect on after mds kicks us off

- be lenient about timing out clients if we are laggy ourselves
- mds prepare_force_open_sessions, then import aborts.. session is still OPENING but no client_session is sent...
- rm -r failure (on kernel tree)
- dbench 1, restart mds (may take a few times), dbench will error out.

- kclient: moonbeamer gets this with iozone -a...
[17608.696906] ------------[ cut here ]------------
[17608.701761] WARNING: at lib/kref.c:43 kref_get+0x23/0x2a()
[17608.707584] Hardware name: PDSMi
[17608.711056] Modules linked in: aes_x86_64 aes_generic ceph fan ac battery ehci_hcd container uhci_hcd thermal button processor
        
[17608.723268] Pid: 19594, comm: sync Not tainted 2.6.32-rc2 #12
[17608.729255] Call Trace:
[17608.731835]  [<ffffffff81252a6d>] ? kref_get+0x23/0x2a
[17608.737209]  [<ffffffff81044f9a>] warn_slowpath_common+0x77/0x8f
[17608.743457]  [<ffffffff81044fc1>] warn_slowpath_null+0xf/0x11
[17608.749395]  [<ffffffff81252a6d>] kref_get+0x23/0x2a
[17608.754634]  [<ffffffffa006e9be>] ceph_mdsc_sync+0xd7/0x305 [ceph]
[17608.761061]  [<ffffffff8145d8b6>] ? mutex_unlock+0x9/0xb
[17608.766618]  [<ffffffffa0078bf3>] ? ceph_osdc_sync+0xe7/0x173 [ceph]
[17608.773199]  [<ffffffffa004d906>] ceph_syncfs+0x4e/0xc8 [ceph]
[17608.779235]  [<ffffffff810f6084>] __sync_filesystem+0x5e/0x72
[17608.785195]  [<ffffffff810f6142>] sync_filesystems+0xaa/0x101
[17608.791122]  [<ffffffff810f61e0>] sys_sync+0x12/0x2e
[17608.796331]  [<ffffffff8100baeb>] system_call_fastpath+0x16/0x1b
[17608.802560] ---[ end trace 36481c4089b3d493 ]---
[17608.807461] BUG: unable to handle kernel paging request at 0000001200000635
[17608.811372] IP: [<ffffffff81252a2c>] kref_put+0x31/0x4f
[17608.811372] PGD 11c7c8067 PUD 0 
[17608.811372] Oops: 0002 [#1] PREEMPT SMP 
[17608.811372] last sysfs file: /sys/kernel/uevent_seqnum
[17608.811372] CPU 0 
[17608.811372] Modules linked in: aes_x86_64 aes_generic ceph fan ac battery ehci_hcd container uhci_hcd thermal button processor
        
[17608.811372] Pid: 19594, comm: sync Tainted: G        W  2.6.32-rc2 #12 PDSMi
[17608.811372] RIP: 0010:[<ffffffff81252a2c>]  [<ffffffff81252a2c>] kref_put+0x31/0x4f
[17608.811372] RSP: 0018:ffff8801137f5e28  EFLAGS: 00010206
[17608.811372] RAX: 0000001200000495 RBX: 0000001200000635 RCX: 0000000000000000
[17608.811372] RDX: 0000000000000000 RSI: 0000000000000040 RDI: 0000001200000635
[17608.811372] RBP: ffff8801137f5e38 R08: 0000000000000000 R09: ffff8801137f5e28
[17608.811372] R10: ffff8801137f5e38 R11: ffffffff8145c5ad R12: ffffffffa00675ae
[17608.811372] R13: ffff880119d02508 R14: ffff880119d02510 R15: 0000000000055fad
[17608.811372] FS:  00007fadcfcd96e0(0000) GS:ffff88002f000000(0000) knlGS:0000000000000000
[17608.811372] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[17608.811372] CR2: 0000001200000635 CR3: 00000001136cd000 CR4: 00000000000006f0
[17608.811372] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[17608.811372] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
        
[17608.811372] Process sync (pid: 19594, threadinfo ffff8801137f4000, task ffff88011bf70480)
[17608.811372] Stack:
[17608.811372]  ffff880103726e18 ffff880103726c00 ffff8801137f5e58 ffffffffa00733f1
[17608.811372] <0> ffff880103726e18 ffffffffa00733a2 ffff8801137f5e78 ffffffff81252a3e
[17608.811372] <0> 0000000000000000 ffff880103726c00 ffff8801137f5ef8 ffffffffa006ea19
[17608.811372] Call Trace:
[17608.811372]  [<ffffffffa00733f1>] ceph_mdsc_release_request+0x4f/0x12a [ceph]
[17608.811372]  [<ffffffffa00733a2>] ? ceph_mdsc_release_request+0x0/0x12a [ceph]
[17608.811372]  [<ffffffff81252a3e>] kref_put+0x43/0x4f
[17608.811372]  [<ffffffffa006ea19>] ceph_mdsc_sync+0x132/0x305 [ceph]
[17608.811372]  [<ffffffff8145d8b6>] ? mutex_unlock+0x9/0xb
[17608.811372]  [<ffffffffa0078bf3>] ? ceph_osdc_sync+0xe7/0x173 [ceph]
[17608.811372]  [<ffffffffa004d906>] ceph_syncfs+0x4e/0xc8 [ceph]
[17608.811372]  [<ffffffff810f6084>] __sync_filesystem+0x5e/0x72
[17608.811372]  [<ffffffff810f6142>] sync_filesystems+0xaa/0x101
[17608.811372]  [<ffffffff810f61e0>] sys_sync+0x12/0x2e
        
[17608.811372]  [<ffffffff8100baeb>] system_call_fastpath+0x16/0x1b
[17608.811372] Code: 49 89 f4 4d 85 e4 be 40 00 00 00 53 48 89 fb 74 0e 49 81 fc 2d 09 0d 81 75 11 be 41 00 00 00 48 c7 c7 62 f8 5c 81 e8 86 25 df ff <f0> ff 0b 0f 94 c0 31 d2 84 c0 74 0b 48 89 df 41 ff d4 ba 01 00 
[17608.811372] RIP  [<ffffffff81252a2c>] kref_put+0x31/0x4f
[17608.811372]  RSP <ffff8801137f5e28>
[17608.811372] CR2: 0000001200000635
[17609.074355] ---[ end trace 36481c4089b3d494 ]---


?- bonnie++ -u root -d /mnt/ceph/ -s 0 -n 1
(03:35:29 PM) Isteriat: Using uid:0, gid:0.
(03:35:29 PM) Isteriat: Create files in sequential order...done.
(03:35:29 PM) Isteriat: Stat files in sequential order...Expected 1024 files but only got 0
(03:35:29 PM) Isteriat: Cleaning up test directory after error.

- osd pg split breaks if not all osds are up...

- mds recovery flag set on inode that didn't get recovered??
- osd pg split breaks if not all osds are up...
- mislinked directory?  (cpusr.sh, mv /c/* /c/t, more cpusr, ls /c/t)

- snaprealm thing
ceph3:~# find /c
/c
/c/.ceph
/c/.ceph/mds0
/c/.ceph/mds0/journal
/c/.ceph/mds0/stray
[68663.397407] ceph: ceph_add_cap: couldn't find snap realm 10000491bb5
...
ceph3:/c# [68724.067160] BUG: unable to handle kernel NULL pointer dereference at 0000000000000088
[68724.071069] IP: [<ffffffffa00805c3>] __send_cap+0x237/0x585 [ceph]
[68724.078917] PGD f7a12067 PUD f688c067 PMD 0 
[68724.082907] Oops: 0000 [#1] PREEMPT SMP 
[68724.082907] last sysfs file: /sys/class/net/lo/operstate
[68724.082907] CPU 1 
[68724.082907] Modules linked in: ceph fan ac battery psmouse ehci_hcd ohci_hcd ide_pci_generic thermal processor button
[68724.082907] Pid: 10, comm: events/1 Not tainted 2.6.32-rc2 #1 H8SSL
[68724.082907] RIP: 0010:[<ffffffffa00805c3>]  [<ffffffffa00805c3>] __send_cap+0x237/0x585 [ceph]
[68724.114907] RSP: 0018:ffff8800f96e3a50  EFLAGS: 00010202
[68724.114907] RAX: 0000000000000000 RBX: 0000000000000354 RCX: 0000000000000000
[68724.114907] RDX: 0000000000000000 RSI: ffff8800f76e8ba8 RDI: ffff8800f581a508
[68724.114907] RBP: ffff8800f96e3bb0 R08: 0000000000000000 R09: 0000000000000001
[68724.114907] R10: ffff8800cea922b8 R11: ffffffffa0082982 R12: 0000000000000001
[68724.114907] R13: 0000000000000000 R14: ffff8800cea95378 R15: 0000000000000000
[68724.114907] FS:  00007f54be9a06e0(0000) GS:ffff880009200000(0000) knlGS:0000000000000000
[68724.114907] CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
[68724.114907] CR2: 0000000000000088 CR3: 00000000f7118000 CR4: 00000000000006e0
[68724.178904] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[68724.178904] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[68724.178904] Process events/1 (pid: 10, threadinfo ffff8800f96e2000, task ffff8800f96e02c0)
[68724.178904] Stack:
[68724.178904]  ffff8800f96e0980 ffff8800f96e02c0 ffff8800f96e3a80 ffffffff8106a3b9
[68724.178904] <0> ffff8800f96e3a80 0000000000000003 00006589ac4ca260 0000000000000004
[68724.178904] <0> 0cb13589944c0262 0000000000000000 ffff8800f96e3b30 ffffffff81ca7c80
[68724.178904] Call Trace:
[68724.178904]  [<ffffffff8106a3b9>] ? get_lock_stats+0x19/0x4c
[68724.178904]  [<ffffffff8106d8c8>] ? mark_held_locks+0x4d/0x6b
[68724.178904]  [<ffffffffa0082a25>] ceph_check_caps+0x740/0xa70 [ceph]
[68724.178904]  [<ffffffff8106a3b9>] ? get_lock_stats+0x19/0x4c
[68724.178904]  [<ffffffff8106a964>] ? put_lock_stats+0xe/0x27
[68724.178904]  [<ffffffffa00840b6>] ceph_check_delayed_caps+0xcb/0x14a [ceph]
[68724.178904]  [<ffffffffa009011f>] delayed_work+0x3f/0x368 [ceph]
[68724.178904]  [<ffffffff8105b194>] ? worker_thread+0x229/0x398
[68724.178904]  [<ffffffff8105b1ee>] worker_thread+0x283/0x398
[68724.178904]  [<ffffffff8105b194>] ? worker_thread+0x229/0x398
[68724.178904]  [<ffffffffa00900e0>] ? delayed_work+0x0/0x368 [ceph]
[68724.178904]  [<ffffffff8146a56e>] ? preempt_schedule+0x3e/0x4b
[68724.306901]  [<ffffffff8105f4d0>] ? autoremove_ceph3:/c# [68724.067160]


filestore performance notes
- write ordering options
  - fs only (no journal)
  - fs, journal
  - fs + journal in parallel
  - journal sync, then fs
- and the issues
  - latency
  - effect of a btrfs hang
  - unexpected error handling (EIO, ENOSPC)
  - impact on ack, sync ordering semantics.
  - how to throttle request stream to disk io rate
  - rmw vs delayed mode

- if journal is on fs, then
  - throttling isn't an issue, but
  - fs stalls are also journal stalls

- fs only
  - latency: commits are bad.
  - hang: bad.
  - errors: could be handled, aren't
  - acks: supported
  - throttle: fs does it
  - rmw: pg toggles mode
- fs, journal
  - latency: good, unless fs hangs
  - hang: bad.  latency spikes.  overall throughput drops.
  - errors: could probably be handled, isn't.
  - acks: supported
  - throttle: btrfs does it (by hanging), which leads to a (necessary) latency spike
  - rmw: pg toggles mode
- fs | journal
  - latency: good
  - hang: no latency spike.  fs throughput may drop, to the extent btrfs throughput necessarily will.
  - errors: not detected until later.  could journal addendum record.  or die (like we do now)
  - acks: could be flexible.. maybe supported, maybe not.  will need some extra locking smarts?
  - throttle: ??
  - rmw: rmw must block on prior fs writes.
- journal, fs (writeahead)
  - latency: good (commit only, no acks)
  - hang: same as |
  - errors: same as |
  - acks: never.
  - throttle: ??
  - rmw: rmw must block on prior fs writes.
  * JourningObjectStore interface needs work?

- separate reads/writes into separate op queues?
- 


greg
- csync data import/export tool?
- uclient: readdir from cache
- mds: basic auth checks

later
- document on-wire protocol
- authentication
- client reconnect after long eviction; and slow delayed reconnect
- repair
- mds security enforcement
- client, user authentication
- cas
- osd failure declarations
- rename over old files should flush data, or revert back to old contents
- clean up SimpleMessenger interface and usage a little. Can probably unify
	some/all of shutdown, wait, destroy. Possibly move destroy into put()
	and make get/put usage more consistent/stringently mandated.

rados
- make rest interface superset of s3?
  - create/delete snapshots
  - list, access snapped version
- perl swig wrapper
- 'rados call foo.bar'?
- merge pgs
- destroy pg_pools
- autosize pg_pools?
- security

repair
- namespace reconstruction tool
- repair pg (rebuild log)  (online or offline?  ./cosd --repair_pg 1.ef?)
- repair file ioctl?
- are we concerned about
  - scrubbing
  - reconstruction after loss of subset of cdirs
  - reconstruction after loss of md log
- data object 
  - path backpointers?
  - parent dir pointer?
- mds scrubbing

kclient
- ENOMEM
  - message pools
  - sockets?  (this can actual generates a lockdep warning :/)
- fs-portable file layout virtual xattr (see Andreas' -fsdevel thread)
- statlite
- audit/combine/rework/whatever invalidate, writeback threads and associated invariants
- add cap to release if we get fouled up in fill_inode et al?
- fix up ESTALE handling
- don't retry on ENOMEM on non-nofail requests in kick_requests
- make cap import/export more efficient?
- flock, fnctl locks
- ACLs
  - init security xattrs
- should we try to ref CAP_PIN on special inodes that are open?  
- fix readdir vs fragment race by keeping a separate frag pos, and ignoring dentries below it
- inotify for updates from other clients?

vfs issues
- real_lookup() race:
  1- hash lookup find no dentry
  2- real_lookup() takes dir i_mutex, but then finds a dentry
  3- drops mutex, then calld d_revalidate.  if that fails, we return ENOENT (instead of looping?)
- vfs_rename_dir()
- a getattr mask would be really nice

filestore
- make min sync interval self-tuning (ala xfs, ext3?)
- get file csum?

btrfs
- clone compressed inline extents
- ioctl to pull out data csum?

osd
- gracefully handle ENOSPC
- gracefully handle EIO?
- client session object
  - track client's osdmap; and only share latest osdmap with them once!
- what to do with lost objects.. continue peering?
- segregate backlog from log ondisk?
- preserve pg logs on disk for longer period
- make scrub interruptible
- optionally separate osd interfaces (ips) for clients and osds (replication, peering, etc.)
- pg repair
- pg split should be a work queue
- optimize remove wrt recovery pushes?

uclient
- fix client_lock vs other mutex with C_SafeCond
- clean up check_caps to more closely mirror kclient logic
- readdir from cache
- fix readdir vs fragment race by keeping a separate frag pos, and ignoring dentries below it
- hadoop: clean up assert usage

mds
- don't sync log on every clientreplay request?
- pass issued, wanted into eval(lock) when eval() already has it?  (and otherwise optimize eval paths..)
- add an up:shadow mode?
  - tail the mds log as it is written
  - periodically check head so that we trim, too
- handle slow client reconnect (i.e. after mds has gone active)
- anchor_destroy needs to xlock linklock.. which means it needs a Mutation wrapper?
  - ... when it gets a caller.. someday..
- add FILE_CAP_EXTEND capability bit
- dir fragment
  - maybe just take dftlock for now, to keep it simple.
- dir merge
- snap
  - hard link backpointers
    - anchor source dir
    - build snaprealm for any hardlinked file
    - include snaps for all (primary+remote) parents
  - how do we properly clean up inodes when doing a snap purge?
    - when they are mid-recover?  see 136470cf7ca876febf68a2b0610fa3bb77ad3532
  - what if a recovery is queued, or in progress, and the inode is then cowed?  can that happen?  
  - proper handling of cache expire messages during rejoin phase?
    -> i think cache expires are fine; the rejoin_ack handler just has to behave if rejoining items go missing

- clustered
  - on replay, but dirty scatter replicas on lists so that they get flushed?  or does rejoin handle that?
  - linkage vs cdentry replicas and remote rename....
  - rename: importing inode... also journal imported client map?

mon
- don't allow lpg_num expansion and osd addition at the same time?
- how to shrink cluster?
- how to tell osd to cleanly shut down
- mds injectargs N should take mds# or id.  * should bcast to standy mds's.
- paxos need to clean up old states.
  - default: simple max of (state count, min age), so that we have at least N hours of history, say?
  - osd map: trim only old maps < oldest "in" osd up_from

osdmon
- monitor needs to monitor some osds...

pgmon
/- include osd vector with pg state
  - check for orphan pgs
- monitor pg states, notify on out?
- watch osd utilization; adjust overload in cluster map

crush
- allow forcefeed for more complicated rule structures.  (e.g. make force_stack a list< set<int> >)

simplemessenger
- close idle connections?

objectcacher
- read locks?
- maintain more explicit inode grouping instead of wonky hashes

cas
- chunking.  see TTTD in
   ESHGHI, K.
   A framework for analyzing and improving content-based chunking algorithms.
   Tech. Rep. HPL-2005-30(R.1), Hewlett Packard Laboratories, Palo Alto, 2005. 

radosgw
 - handle gracefully location related requests
 - logging control (?)
 - parse date/time better
 - upload using post
 - torrent
 - handle gracefully PUT/GET requestPayment



-- for nicer kclient debug output (everything but messenger, but including msg in/out)
echo 'module ceph +p' > /sys/kernel/debug/dynamic_debug/control ; echo 'file fs/ceph/messenger.c -p' > /sys/kernel/debug/dynamic_debug/control ; echo 'file ' `grep -- --- /sys/kernel/debug/dynamic_debug/control | grep ceph | awk '{print $1}' | sed 's/:/ line /'` +p  > /sys/kernel/debug/dynamic_debug/control ; echo 'file ' `grep -- === /sys/kernel/debug/dynamic_debug/control | grep ceph | awk '{print $1}' | sed 's/:/ line /'` +p  > /sys/kernel/debug/dynamic_debug/control